196 Earl W. Benjamin 



The size and shape of the egg is shown by Curtis (1911 a)^and by Surface 

 (1912) to be due partly to the structure of the oviduct, which may probably 

 be considered an inherited character as claimed by Newton (1893-96). 

 This is in accordance with the view of Thompson (1908). This physical 

 influence on the size and shape of the egg described by Thompson (1908) 

 is denied by Horwood (1909), but without convincing evidence. 



The shape of the egg seems to depend on its size, according to Curtis 

 (1914 a). The same author shows good correlations between the two 

 dimensions of eggs, and between either of these dimensions and the weight. 

 This agrees with the conclusions of Pearl and Curtis (1916). 



Curtis (1914 a) claims that the larger eggs are due to a greater relative 

 deposition of egg white, while Atwood (1914) finds indications contrary 

 to this. ^ 



The size of the egg seems to be affected by the feed, according to 

 Atwood (1914), and the same author shows a marked seasonal fluctuation 

 in the weight of eggs laid, the weight gradually increasing from July 

 to February and decreasing from March to July. , This agrees with 

 Curtis (1914 a) and with F6r^ (1898 b), who claim that the eggs are 

 smaller at both the beginning and the end of the litter. Rice, Nixon, and 

 Rogers (1908) and Riddle (1911) show a striking effect of the amount of 

 food consumed on the number of eggs produced. According to these 

 workers, both the amount of food consumed and the number of eggs pro- 

 duced seem to be variable factors agreeing in their seasonal fluctuations 

 with the size of the egg, as just noted. Curtis (1914 a) also shows a grad- 

 ual reduction in size for the successive eggs in the clutch. Hadley (1919) 

 shows a monthly fluctuation in the egg weight of thirty-nine White 

 Plymouth Rocks Tvhich corresponds closely with the monthly numerical 

 production. He finds also that the percentage increase in egg weight 

 during the two modal months of increased production (April and Sep- 

 tember) is positively indicative of the relative annual numerical produc- 

 tion of the respective birds. 



.^According to Curtis (1914 a), the size of the eggs increases as the bird 

 matures. Curtis states also that the variations among the eggs produced 

 by individuals were not so great as the variations in the flock's production, 

 and seemed to diminish as the birds matured. This agrees with the 



2 Dates in parenthesis refer to Bibliography, page 310. 



